3C (Reading and Interactive)

What Is Synthesis?

You’ve probably heard the word synthetic before. It comes from the word synthesis, which basically means “putting things together to make a whole.” If you take a pile of wooden boards and build a house from them, that is a kind of synthesis. If you take the contents of a bag of groceries and put them together to make a gourmet meal, that too is a kind of synthesis. When you make something new by putting together different parts, you’re synthesizing.

Chemical Synthesis

But when we say that a chemist like Percy Julian synthesized this substance or that, what are we talking about? Well, chemists put things together too, but the things chemists put together are much smaller than a house or a gourmet meal. Chemists synthesize molecules.

Why Do Chemists Synthesize Molecules?

There can be many reasons, too numerous to mention here, but one very important reason is to make things in the lab that previously only occurred in nature. This is what Julian became famous for in his lifetime.

Why Make Substances in the Lab If They Already Occur in Nature?

Often, important and useful substances occur in nature only in small amounts, and they can be very difficult and costly to extract from their natural sources. You will learn about a specific example later in this site when you read about Julian’s breakthrough synthesis of a substance called physostigmine, which occurs naturally in a type of bean. (See Julian’s Big Breakthrough: 19311935, Physostigmine and Glaucoma.)

Medicines are examples of the kinds of things you want to be able to make in the lab, because once you figure out how to synthesize the molecule that constitutes a medicine, then others (we call them “chemical engineers”) can figure out how to do your synthesis on a large scale, producing the medicine in large quantities and bringing it to many people. Synthesizing molecules that enabled more people to have access to life-saving or life-changing cures was Julian’s greatest achievement as a chemist.

The Process

Figuring out how to synthesize a molecule can be very difficult. It can take many steps or chemical reactions. When chemists attempt to synthesize a molecule, they start with starter substances or building blocks and do various things to these substances that cause chemical reactions. The reactions break apart the molecules of the starter substances and reassemble the atoms in a different way. Each chemical reaction should bring the chemist one step closer to the final product he or she is trying to make. Chemists can bring about the chemical reactions in a number of ways, including treating the substances with heat, pressure, sound, electricity, or any number of other things that will make the molecules break apart and reassemble. Figuring out what substances to start with, what to do to these substances to cause the right chemical reactions, and in what order the reactions need to take place can be very tricky, complicated business, but it’s what chemists do every day.

One of the goals of a synthesis is to get from your starting substances to the final product in as few steps, or as few chemical reactions, as possible. There is usually more than one way to synthesize a molecule, but the fewer the steps the better because when you scale up a synthesis for mass production, what was one little extra step in the lab may cost thousands of extra dollars in the factory. Also, there is something inherently “beautiful” to chemists in achieving the most efficient synthesis. Julian’s synthesis of the complicated physostigmine molecule took 11 steps. His competitor had been attempting a synthesis that involved many more steps, and Julian knew he could do better.

A Synthesis Game

Try your hand at achieving a synthesis in as few steps as possible by playing the Screwdriver “Synthesis” Game. In this game you’ll get a taste what its like to try to assemble something not only by choosing the right steps, but also by choosing the fewest right steps.

How to Play: The bit of the screwdriver does not fit into the handle. You must add adapters one at a time until you have an adapter on the end that the bit will fit into. Your objective is to assemble or “synthesize” the screwdriver using the fewest number of adapters as possible. To add an adapter to the screwdriver, single-click on it. If it will not fit, the game will tell you. If it fits, it will appear in place. Keep adding adapters until you can add the bit.